1. Technical Field
The present disclosure relates to a semiconductor device and a manufacturing method thereof, and more particularly relates to a semiconductor device containing silicon carbide and a manufacturing method thereof.
2. Description of the Related Art
Silicon carbide (SiC) is a semiconductor material which has a larger band gap as compared to silicon (Si) and which has a high degree of hardness. SiC has been applied to power devices such as switching devices and rectifying devices, for example. Power devices using SiC have an advantage that power less can be reduced, for example, in comparison with power devices using Si.
The metal-insulator-semiconductor field-effect transistor (MISFET) and the Schottky-barrier diode (SBD) are representative of semiconductor devices using SiC. The metal-oxide-semiconductor field-effect transistor (MOSFET) is a type of MISFET. The junction-barrier Schottky diode (JBS) is a type of SBD.
A JBS has a first conductivity type semiconductor layer, multiple second-conductivity-type regions disposed in contact with the first conductivity type semiconductor layer, and a Schottky electrode which forms a Schottky junction with the first conductivity type semiconductor layer and the multiple second-conductivity-type regions. The JBS exhibits lower leak current when reverse bias is applied to the JBS as compared to the SBD, due to the multiple second-conductivity-type regions.
Japanese Unexamined Patent Application Publication No. 2005-243715, for example, discloses that leak current when reverse bias is applied to the JBS is even further reduced by forming a Schottky electrode disposed above the first-conductivity-type semiconductor layer and a Schottky electrode disposed above the multiple second-conductivity-type regions from different metals.
Japanese Unexamined Patent Application Publication No. 2005-243715 discloses a JBS having a first Schottky electrode disposed above the first-conductivity-type semiconductor layer excluding portions of the first-conductivity-type semiconductor layer which are at the perimeter of the second-conductivity-type regions, and a second Schottky electrode disposed above the second-conductivity-type regions and portions of the first-conductivity-type semiconductor layer which are at the perimeter of the second-conductivity-type regions.
A metal having a large work function is used for the first Schottky electrode, and a metal having a small work function is used for the second Schottky electrode. Due to this configuration, leak current when reverse bias is applied to the JBS is further reduced as compared to a configuration where both the first-conductivity-type semiconductor layer and the second-conductivity-type regions are both covered by the second Schottky electrode.